Functional analyses of basement membrane components in association and dissociation of hemidesmosomal adhesion structures

在该基金的支持下，我们取得了以下成果：1我们成功地分离了基底膜（BM）组分，并制备了一组针对BM组分的单克隆抗体。使用抗体，我们证明，腺肌上皮细胞具有上皮型半桥粒（HD）和平滑肌型粘附连接作为细胞-基质粘附装置。我们还发现，层粘连蛋白γ2亚基的加工促进了层粘连蛋白5在基质中的周转。2我们证明了BP 180/XVII型胶原的胞外结构域的切割是由细胞表面的基质金属蛋白酶完成的，而不是在细胞内膜中。3我们研究了简单上皮中的HD型粘附结构，发现BP 180，在结肠上皮细胞中，除了由网蛋白和整联蛋白α6β4组成的II型HD组分之外，在肾小管上皮细胞中，除了整联蛋白α6β4之外没有HD组分，这表明存在新的粘附结构。4我们从兔平滑肌细胞中分离出180/200 kD蛋白，并将其鉴定为哺乳动物共溶蛋白，一种中间丝蛋白，并证明该蛋白在包括肌上皮细胞在内的所有四种类型的肌肉细胞中表达，与其他IF蛋白如角蛋白和结蛋白相互作用。

Supported by this grant, we have obtained following achievements.1 We have succeeded in isolating a basement membrane (BM) fraction and prepared a panel of monoclonal antibodies to BM components. Using the antibodies we demonstrated that glandular myoepithelial cells have both the epithelial-type hemidesmosome (HD) and the smooth muscle-type adherens junction as cell-matrix adhesion apparatus. We also showed that processing of laminin γ2 subunit facilitates the turnover of laminin 5 in the matrix.2 We demonstrated that the cleavage of the extracellular domain of BP180/type XVII collagen is done by a matrix metalloproteinase on the cell surface, not in the intracellular membrane.3 We investigated HD-type adhesion structures in simple epithelia, and found an expression of BP180, in addition to type II HD-components consisting of plectin and integrin α6β4, in colon epithelial cells, and no HD component except integrin α6β4 in uriniferous tubular epithelial cells, suggesting the presence of novel adhesion structure.4 We isolated a 180/200 kD protein from rabbit smooth muscle cells and identified it as mammalian synemin, an intermediate filament protein, and demonstrated that this protein is expressed in all four types of muscle cells including myoepithelial cells, interacting with other IF-proteins such as keratin and desmin.